Patients in this study will be allocated to cohorts as below. Cohort A will include postmenopausal patients with hormone receptor-positive breast cancer who receive aromatase inhibitor (AI) as neoadjuvant therapy concurrently with administration of 6 or 8 doses of WT1 anti-cancer immunotherapy (WT1 ASCI)/placebo starting on Day 0. AI treatment will be administered daily for duration of either 18 (if 6 doses of WT1 ASCI/placebo) or 24 weeks (if 8 doses of WT1 ASCI/placebo).